1. Technical Field
The present invention generally relates to a light-emitting diode (LED) type cabin reading light. More particularly, the present invention pertains to an LED type cabin reading lamps for replacing state of the art filament lamps used on aircraft and similar other transportation vehicles, and method for monitoring the same.
2. Description of the Prior Art
According to classical physical principles, power (P) is the rate at which work is performed or energy is transferred. In other words, power may be defined as the amount of energy required or expended in a given unit of time. In the International System of Units (SI) system of measurement, power is measured in watts (W). One watt is equivalent to one joule of energy transfer per second. The instantaneous electrical power (P) delivered to an electrical component is given by the relation: P(t)=I(t)·V(t), where P(t) is the instantaneous power, measured in watts, V(t) is the potential difference (or voltage drop) across the component, measured in volts; and I(t) is the current flowing through it, measured in amperes. If the component is a resistor, then: P=I2·R=V2/R where R=V/I is the resistance, measured in ohms.
Exemplary state of the art filament-based reading lamps used on aircraft such as the Boeing 777 and 747-400 (such as Model Nos. 2059 and 2058X) may consume 10 watts with an average lamp life of approximately 8,000 hours. Further, filament-based reading lamps used on aircraft such as the Boeing DC-9, 737, 757, and 767 (such as Model Nos. 2232, 2233, 2233B, 307SB, and 674SB) may consume 44 watts with an average lamp life of about 2,000 hours. Notably, the lamp-operating power is consumed from a burnt fuel-based source on board the aircraft. If the filament type reading lamps could be replaced with lamps that consume less power with substantially equivalent lumen intensity with a substantially longer average lamp life (such as an LED type lamp), the replacement lamp could well cut fuel usage and operating cost during the life of the replacement lamp.
Similar to a conventional diode, a light-emitting diode or so-called “LED” comprises a chip of semi-conducting impurity-doped material so as to create a junction. As in other diodes, current flows easily from the cathode side of the junction to the anode side or the junction, but not in reverse. Charge-carriers flow into the junction from electrodes with a potential difference therebetween. When charge carriers fall into lower energy levels, energy is released in the form of photons (light), thereby emitting light as a light-emitting diode or LED.
It should be noted that the prior art is not silent in terms of cabin reading light-type lamp assemblies and means for monitoring the same. Some of the more pertinent prior art relating to cabin reading light assemblies; certain means for enabling the use of light-emitting diode lamp assemblies in combination with existing filament or incandescent lamp assemblies; and lamp system monitoring means are briefly set forth in U.S. Pat. Nos. 5,377,087; 7,153,008; and 4,475,196, respectively. These abstract type descriptions of these disclosures are set forth hereinafter.
U.S. Pat. No. 5,377,087 ('087 patent), which issued to Yoon, discloses a Passenger Reading Light. The '087 patent teaches an orientable passenger reading light assembly for vehicles, which light assembly comprises a two-part removable bezel arrangement. The lower part of the bezel is freely rotatable to disguise the method of relamping by requiring correct manipulation of the upper bezel part to allow release and removal of the bezel arrangement. A continuously adjustable ball and socket arrangement permits varying the orientation of the light over a wide range such as a 25 degree spherical zone. A simplified locking mechanism may be engaged in any position without tools, to prevent adjustment by passengers. When the locking mechanism is disengaged, enough friction is provided to maintain the orientation despite environment vibration.
U.S. Pat. No. 7,153,008 ('008 patent), which issued to Grote, III et al., discloses a Conversion Cradle Incandescent Lamp to LED Lamp. The '008 patent teaches an LED lamp mounting assembly for use in motor vehicle lamps. The LED lamp mounting assembly preferably connects a LED lamp to a pre-existing incandescent lamp socket in a motor vehicle. The LED lamp mounting assembly therefore allows a LED lamp to be operated from incandescent lamp hardware. In one embodiment, the LED lamp mounting assembled includes a LED lamp assembly, a heat sink, a cradle, printed circuit boards and an electrical connector. The electrical connector is insertable into the incandescent lamp socket and connects to the printed circuit boards. The printed circuit boards power the LED lamp assembly and the heat sink adsorbs excess heat created by the LED lamp assembly. The motor vehicle lamp becomes a LED lamp without any changes to the existing incandescent lamp hardware.
U.S. Pat. No. 4,475,196 ('196 patent), which issued to La Zor, discloses an Instrument for Locating Faults in Aircraft Passenger Reading Light and Attendant Call Control System. The '196 patent teaches a testing instrument especially adapted for use in locating faults in the passenger reading light and flight attendant call control systems which are used in jumbo jetliners. The testing instrument includes a selection means for designating one of a plurality of series connected passenger locations. Each passenger location includes a proximately located group of two or three passenger seats. The instrument includes indicators for registering data transmitted from the passenger location to a section timer that controls input from and output to passenger locations in an aircraft cabin on a timed, multiplexed basis. The instrument also monitors transmission of data from the section timer to the selected passenger location and includes detectors for registering faults in timing and parity pulses. The instrument includes test controls to create particular conditions of the reading light and attendant call controls, and also a meter for detecting abnormalities in voltage drops at each of the serially connected passenger locations.
It may seen from a consideration of the foregoing disclosures as well as from a general consideration of the related arts, that the prior art does not teach a self-contained light-emitting type diode lamp assembly, which may effectively function to replace filament type or incandescent type lamp assemblies by simulating a low resistance through the diode lamp assembly such that means for detecting high resistance or breaks in filament type circuits do not otherwise prompt bulb replacement signals when a high resistance light-emitting diode is placed into a socket designed to receive low resistance incandescent lamps. The prior art thus perceives a need for a diode lamp assembly according to the foregoing specifications.